Rotary seal for pumps



c. A. NAMUR 2,339,099 ROTARY SEAL FOR PUMPS 2 Sheets-Sheet l Jan. 11,1944.

Filed Dec. 14, 1940 fiverzz ar' I lv a 9 ,v :W//////// w 0 -n w 3 .III.W W .2 W 2 2 W 2 Ou-I/ 2 Sheets-Sheet 2 J2me Jan. 11, 1944. c. A. NAMURROTARY SEAL FOR PUMPS Filed Dec. 14 1940 V Patented "Jan. 11,1944

' 'ul u'rso srArss PATENT OFFICE oruir fi zzarums I Carl A. Namur,Kenosha, Specialty Brass Company,

osha, Wim,

Wia, assignor to- Incorporated, Ken

a corporation of Wisconsin The invention relates to. a rotary seal forpumps. It is particularly useful in connection with enclosed impellerpumps-employed in pump- "ing liquids such as milk, etc. It isapplicable, however, to devices other than sanitary pumps. An object ofthe invention is to provide simple and eifective sealing means which maybe employed with enclosed impeller pumps, whereby the back pressurecreated by the impeller is nu lized for maintaining an eflectivelseal.Another object of the invention is to provide apump with internal rotaryseal means whereby any sudden back pressure caused by throttling orcompletely utting oil the discharge side of the pump serves merely tomake the seal more effective. A further object is to provide a pump andan internal rotary seal mechanism in which springs are entirely doneaway with and in which a minimum 1 In order to take care of such periodsof high pressure, it is necessary to use a high spring tension, 9.spring tension which is much greater than need be applied under ordinaryoperating conditions. Thus for a greater period of the time the sealiscreating excessive friction over that which is needed.

I have found that with a pump'having an enclosed or shrouded impeller asimple rotary seal structure may pump, which tension or, in fact, anyspring tension whatsoever, while at the same time the above periods ofhigh pressure are utilized to increase thesealing effect. A pump with anenclosed impeller produces a pressure at the point where the shaftenters the housing, which is just opposite ,thatof parts is employed foreffectively maintaining I the seal. Other specific objects andadvantages 1 will appear as the specification proceeds.

The invention is described in its preferred embodiment by the accowhich- Figure 1 is a longitudinal sectional view of a pump casing andimpeller equipped with sealing means embodying my invention; Fig. 2, abroken view showing in section the parts enclosing the drive shaft for,effecting a seal thereof; Fig. 3, a plan view of the sealing ring;'Fig.4, a section thereof; Fig. 5, a plan view of the stationary ring carriedby the retaining ring of the casing; Fig. 6, a section thereof and Fig.7, a cross sec tional View of the impeller-and-impeller shaft,

showing the flat surfaces thereof in contact.

It has been common heretofore in sanitary centrifugal pumpstd use-packstumng boxes.

i However, with a pack stufllng box there is apos- "sibility of milkentering, V box is rather difiicult to clean,,an insariitary con-.

dition may result.

panying drawings, in

and, since the stuffing produced by an open impeller. l With a shroudedor partially shrouded centrifugal impeller, there is a pressure at theplace be employed on the inside of the does not require excessive springwhere the pump shaft enters the housing which is practically equal tothe discharge pressure of the pump. This pressure is utilized forforcing be few simple sealing parts, which will be described hereinafterin detail, producing an efiective seal.

Any suitable type of pump may be employed. In the illustration given, Ihave shown a'pum-p greater detail in Patent No. 1,809,526. It isbelieved unnecessary to describe the pumpin great detail.

The drive shaft of the pump is indicated by the numeral l0, and it ismounted inthe bearing II,

. the bearing and support therefor being of well driving the shaft l0.Shaft to, provide a bearing surface for receiving the seal- It has alsobeen common to use external rotary seals, that is, seals located outsidethe pump =lwusing. In such structures, pressure between the rotary andstationary part is applied by a sp ins- V v This style of seal isem'ployed on'a pump with produces a suction or.

an open impeller which reduced pressure at the place where the shaftenters the pump housing. The difllculty with this structure, however, isthat should the valve or the discharge side of the pump be suddenlydeveloped tends to force the external type of roknown, construction. Anysuitable power, such as, for example, a motor may be employed for Iliisreduced at I! together and thus ing members which will be laterdescribed. The

shaft is further reduced at l3 to provide a surface for supporting theimpeller, and the extreme end of the shaft is threaded at H. a

As'shown more clearly in Fig. 1, an impeller II of the enclosed type isprovided centrally with an ap'ertured hub which is received about theshaft portion l3. The impeller is provided at its front side with anwith-the inlet 20. The discharge opening H. A threaded nut member I8 isemployed for maintaining the impeller upon inlet opening it aligned theshaft i 0.

I throttled or completely shut off the high pressure The casing E of thepump may be of any-suitable construction. In the illustration .given, itprovides, together with the front plate iii, an impeller chamber forreceiving the impeller II impeller has a peripheral ring C, which isformed taining ring n thereon. A flat surface the resilient drive 2 andthe liquid discharged therefrom. The casing is provided with an outlet19; The removable front plate E" is provided with an inlet pipe 20.Threaded bosses 2| carried by the easing E receive th clamp members 22',which are employed for releasably locking the front plate E in position.

The seal can be tional view shown in Fig. 2. that a resilient drive ringA the-forward portion l2 of the shaft Ill and extends beyond the portionII to a position around the reduced portion l3 of the shaft It. On theinside of the drive ring A is a rotating seal ring seen more clearly inthe see- It will be observed B made of bearing bronze or other suitablemate .8 bears against the stationary of stainless steel or other rial..The ring suitable material.

The width of the resilient drive ring A and that of the rotating sealring 3, should preferably be such that when the two rings are placedside by side in engagement with each other and with the seal ring B andin contact with the stationary ring C, the drive ring A, whenuncompressed, extends'beyond the forward portion I! of the shaft III.The rings A and B may be rotatably and slidably mounted on the shaft Hi.

The drive ring A, although it may be rotatably and slidablymounted onportion l2 of the shaft [0, should be in frictional engagement with theshaft and should be so closely fitted to the shaft that it will becaused to rotate by the rotation of the shaft. The frictionalengagementwith the impeller Ill.

The ring C is pressed into the stationary rewhich is provided with aninterlocking connection with the pump casing E, a resilient seal 24being employed between the interlocking portions of the members. Ifdesired, the ring and stationary retaining ring D may be formed in onepiece.

The impeller I5 is mounted on ll of the shaft ill for axially slidablemovement "Won the impeller shaft ll engages a flat surface I! on theinside of the impeller hub, causing the shaft and impeller The nut I8 isthen applied portion ll'of the shaft Ill and to the threaded theimpeller hub is in engagetightened iintil 'ment with the resilientdrive'ring A. The nut la is then further tightened to cause theresilient drive ring A to be compressed under the pressure of theimpeller hub. When the drive ring A is thus compressed, it urges'theseal ring 3 into sealing engagement with the stationary ring C.

The impeller I5 is thus slidablelongitudinally on the reduced portion I!of the shaft II when ring A is compressed. The nut IS on one side andthe shoulder of the portion I! of the shaft Ill on the other sideprovide limits for this movement on the shaft.

when the resilient drive ring. A is compressedby the tightening of thenut It, the ring is arranged so that it is subject to pressure'which maybe created within the impeller chamber. Thus if pressure is exerted uponthe periphery of the compressed drive ring A, it will tend to force thering-closer to the. portion I! of the shaft l0 and to urge the ring Binto tighter engagement with the stationary ring C.

Asshown more clearly in Figs. 2 and 4, the ring B, which has a veryclose fit with the shaft II, is provided on its inner side with cutawaycorner portions 23.

is received about drive ring A is also in- This 45 chamfer placed on thereduced end i tween the shaft, the

is discharged through the of the seal between each face and beginning onthe inside diameter is for the purpose of allowing some relief bering B,and the stationary ring 0. This relief also reduces the bearingfriction.

Operation,

In the operation of the apparatus, milk enters through the inlet 20 andthen passes through the impeller opening it into the impeller II. Itperipheral opening i1 and passes outthrough pipe I9. 7 Y

The discharge of thellquid from the enclosed impeller creates a backpressure within the impeller chamber, which pressure causesithe compressed drive ring A to be pressed more tightly against the seal ring B.Thus the periphery of the compressed resilient drive ring A is sub-:lected to the same pressure as that which exists at the point ofdischarge of the liquid from the impeller.

This pressure against the periphery of the drive ring A urges it closerto the reduced portion 12 of the shaft l0 and causes the side of thedrive ring to be more tightly pressed against the seal ring B. Therotating seal ring 13, in turn, is pressed more tightly against thestainless steel stationary ring C, thus effecting a tighter seal.

As any excessive pressure i developed, the seal thereby becomes moreeffective. At the same time, under ordinary operating pressures,nounusual pressure or friction is found necessaryfand the use of aspring is entirely. avoided.

In the pumping operation, the shaft I0 is rotated by suitable powermeans, and the impeller I5 is driven thereby, the flat surface It on theshaft engagin peller hub. The fluid pressure produced by the dischargeof liquid from the impeller creates a pressure upon the ring A, causinga tightening the rings B and C.

the p y After the pumping operation,

Upon release readily disassembled for cleaning. of the clamp 22, themaybe removed, and then upon the un'scre of the nut it the impeller I!may be slipped off of the shaft 10. The drive ring A and the seal ring13 may now be slipped oil. This leaves only the stationary parts 0 andD, which are readily accessible both from the inside and the outside. Inassembling the parts. the sealing ring B is slipped upon theshaft'portion l2 and the resilient drive ring A slipped on the someportion of the shaft. The impeller I5 is then slipped is threaded ondrive ring A position and locked by means of the clamp 22. The pump isthen ready for the next pumping operation.

This application is a continuation in partof my copending applicationSerlaLNo, 226.999,

broadly as permissible in view of the prior-art.

I claim: I 1. A rotary seal for a drive shaft arranged in ppeasingeeuippedwithastationarnealins the flat surface l5 of the im-jfront casing member E' which it is intended impeller along said shafttoward said drive ring to compress the resilient drive ring laterallyalong the axis of the shaft whereby the drive ring is expanded radiallyoutwardly and the sealing ring is urged into sealing engagement with Ithe stationary surface, the entire periphery of the drive ring beingfree to move radially and being exposed to the interior of th casingwhereby fluid pressure within the casing may compress the drive ringradially inwardly to expand the same laterally along the shaft andtighten the seal between the sealing ring and the stationary surface.

2. In a pump casing equipped with a drive shaft extending thereinto,a'rotary seal comprising a stainless steel plate carried by said casingand enclosing said drive shaft, 9. bronze sealing ring rotatably mountedon said shaft and engagmg said plate, said ring being chamfered on itsinner edges adjacent said drive shaft, a compressible annular resilientdrive ring extending about said shaft adjacent said metal ring with oneside of said drive ring in frictional engagement with said metal'ring,said drive ring having a laterally fiat outer peripheral surface, eachof said rings being longitudinally slidable with respect to said shaft,a pumping impeller in said casing slidably mounted on said shaft androtated thereby, said impeller being pressed against the other side ofsaid driVe ring to bring the sealing ring into sealing engagement withsaid plate to compress the ring laterally along the axis of said shaftand produce outward radial expansion 1 thereof, the outer peripheralsurface of the ring being free to move radially and being engaged onlyby liquid under pressure within said casing, the liquid exerting inwardradial pressure on the periphery of the ring to urge the same towardlateral expansion whereby the seal between the sealing ring and theplate is tightened, and means for maintaining said impeller in positionto compress said drive ring.

3. A device as set forth in claim 1, wherein:

, the inner peripheral surface of the drive ring is substantiallycylindrical and is in engagement throughout with the drive shaft.

' CARL A. NAMUR.

